The Wikimedia Foundation's core features team developed and released this new notification system in 2013, and it is now deployed on all Wikipedias and sister sites -- with very positive community response, as summed up in this blog post. To learn more about Notifications, read this FAQ page, this project hub and/or Testing page.

We have now completed this first release and core feature development has ended for this project. Going forward, any new features or notifications will be developed by teams that need them, based on this developer guide.

Please contact us right away if your community seriously wishes to postpone deployment of Notifications. Though our plan is to deploy to most wiki sites, we may exclude a couple sites that have special needs, if explicitly requested by their communities, with a strong rationale for why this release needs to be postponed on their site.